<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            padding: 0;
            margin: auto 0;
        }
        
    </style>
</head>
<body>
    <input type="button" onclick="alert('结果是' + result)" value="+" style="width:30px; height: 30px; background-color: violet;">
    <input type="button" onclick="alert('结果是' + minus)" value="-" style="width:30px; height: 30px; background-color: rgb(11, 239, 255);">
    <input type="button" onclick="alert('结果是' + multiplication)" value="×" style="width:30px; height: 30px; background-color: rgb(11, 239, 255);">
    <script>
        var num1 = prompt('输入第一个数字');
        var num2 = prompt('输入第二个数字');
        var result = parseInt(num1) + parseInt(num2);
        var minus = parseInt(num1) - parseInt(num2);
        var multiplication = parseInt(num1) * parseInt(num2);
        // alert('结果是' + result);
    </script>
</body>
</html>